Method for the preparation of pigmented curable polyester molding compounds

Abstract

The invention relates to a process for preparing a pigmented curable molding compound comprising mixing together an unsaturated polyester resin, a thermoplastic polymer, a color paste and optionally a filler, and is characterized in that the color paste is obtained by dissolving pigment particles in a solution of a thermoplastic polymer in a suitable solvent. The invention further relates to the color paste itself and to homogeneously and uniformly colored moldings obtained thereform.

What is claimed is:  
     
       1. A process for preparing a pigmented curable molding compound comprising: 
       a) preparing a color paste by:  
       i) combining:  
       I. a first thermoplastic polymer;  
       II. a suitable solvent; and  
       III. pigment particles;  
       ii) grinding said pigment with (I) and (II) to form a color paste;  
       b) mixing together:  
       A. an unsaturated polyester resin, and  
       B. a second thermoplastic polymer, in a weight ratio A:B of 0.4 to 10, the total of A and B being 100 parts by weight (pbw)  
       C. 3-40 pbw of the color paste of (a),  
       D. 0-450 pbw of a filler,  
       E. 0.2-4 pbw of a radical initiator, as well as  
       F. optionally further customary additives.  
     
     
       2. Process according to  claim 1 , wherein the first thermoplastic polymer is selected from vinylaromatic polymers, polyolefinic polymers, acrylic-based polymers, polyvinyl acetate polymers, saturated polyesters and combinations thereof. 
     
     
       3. The process of  claim 1  wherein the color paste is obtained by dispersing 20-80 pbw pigment particles in 80-20 pbw of a solution of 10-60 wt-% of the first thermoplastic polymer in 90-40 wt.-% of the suitable solvent, the wt.-% being based on the total weight of said first thermoplastic polymer and the suitable solvent. 
     
     
       4. The process of  claim 1  further comprising curing said curable molding compound to form homogeneously and uniformly colored mouldings, comprising 
       10 to 20 wt. % of cured polyester resin;  
       1 to 20 wt. % of a saturated polyester, replaced up to 50 wt. % of its weight by another thermoplastic polymer;  
       0.5 to 5 wt. % of pigment particles;  
       5 to 65 wt. % of fillers;  
       0.1 to 2 wt. % of a thickening agent;  
       10 to 65 wt. % of glass fibres;  
       and having a maximum color deviation ΔE max  from the average color value (determined according to DIN 6174) below 0.3.  
     
     
       5. The process of  claim 1  wherein said first and second thermoplastic polymers are different.